vm_inout_attach
err = vm_inout_attach(&vm->ioports, port, IOPF_DEFAULT, func, arg);
err = vm_inout_attach(&vm->ioports, port, IOPF_DRV_HOOK, func, arg);
int vm_inout_attach(struct ioport_config *ports, uint16_t port, uint16_t flags,